For capturing LF images, the type of visual data adopted in this work, two main practical setups are currently available, notably using a high density array of cameras or a lenslet LF camera.
In a lenslet LF camera, as illustrated in Figure REF , a micro-lens array, consisting of a set of micro-lenses, is placed at the focal plane of the main lens at a given distance from the photo sensor [1]}. This allows
for the incoming light to be split based on its direction, and projected onto the photo sensor area. Each micro-lens can be thought of as a small camera, capturing light rays from a specific point in the scene, thus acquiring a so-called micro-image [2]}. A sample of a full set of LF color demosaiced micro-images is shown in Figure REF (a). A set of SA images, corresponding to different viewpoints of the scene can then be rendered from the micro-images. The set of rendered SA images can be considered as a multi-view SA array. Examples of a multi-view SA array and the corresponding 2D central SA image are shown in Figure REF (b) and Figure REF (c), respectively. Since each 2D SA image `sees' the scene from a slightly different viewpoint, the full set of 2D images provides angular variations of the scene, which is a distinctive characteristic of LF imaging. The LFFW dataset proposed in this paper was captured with a Lytro Illum camera [3]}, which multi-view SA array includes \(15\times 15\)  SA images, each SA image with a spatial resolution of \(625\times 434\)  pixels.
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